1. Field of the Invention
This invention relates to end closures for cable splice closures to provide an hermetic seal at the cable entrance and in one aspect to an improved seal for a pedestal splice closure where service wires are spliced to selected wire pairs of a loop of telephone cable.
2. Description of the Prior Art
Providing a seal for a cable splice closure which will provide a high degree of protection to the spliced area of the cable against moisture entry, dust, bugs. etc. and still have a closure which is easy to apply and is reenterable is an area of inventive endeavor challenged by many.
There have been prior closures which have used mating collars to define a preformed band about the cables and there have been closures which provided the degree of environmental sealing necessary. There has not been a closure which could provide the desired sealing, repeated reentry and not require tools to allow reentry, or tools to create the seal in a pedestal type splice closure.
An early pedestal closure is shown in U.S. Letters Pat. No. 3,557,299 which discloses a loop formed in a cable with the loop fitted into a molded base through a retainer to which the cable portions are fixed by clamps. A seal is formed about the cable portions by an elastic sleeve clamped about the cables. A channel is formed about the sleeve and is filled with a mastic to assist in forming the seal about the cables created by the compression plates. The drop wires enter through perforations in the base and are held in place by pack nuts. The protective cap or dome for the closure was sealed to the base by an abutting O-ring and a ring clamp.
A pedestal closure which is sealed by an encapsulating splice housing is shown in U.S. Letters Pat. No. 4,488,013. The housing in this patent is adapted to be filled with the sealant and a seal is formed about the legs of the cable by a stepped or tapered lower portion formed of sufficiently soft material to be cut to fit the two legs of the cable. There is no teaching of reentry.
U.S. Letters Pat. No. 4,341,922 is directed to a strain-relief brace for a cable splice case and discloses an end seal for forming a seal with a cable at the end of a closure. This seal description teaches the use of strips of mastic tape convolutely wound about the cables at the required locations and to the required thickness, sufficiently to slightly overfill the designated spaces within the cable collars. The collars are then applied and split half washers are used at the ends. The collar halves are drawn together by fasteners. The seals formed as described require considerable time and force to get the mastic to flow to the point of sealing the ends and having the washers bow or bulge under the force of the surplus mastic. The use of the bolt type fasteners and threaded sleeves require additional tools and time to prepare an effective seal.
Other prior art includes the closure where the cables and drop wire or service wire and ground wires are wrapped with the mastic tape. A plastic covering is then placed about the mastic tape. A molded dome is placed over the coiled wire and splices and then a prestretched core-supported rubber-like sleeve is placed over the end of the dome, which is placed on or near the wrapped mastic. The support core is then removed to shrink the sleeve tightly over the end of the dome and the covering of the mastic. The sleeve must be cut and removed to afford reentry and subsequently replaced following any service work on the splice.
The use of an O-ring to seal one end of a cylindrical sleeve of resilient or elastic material is shown in U.S. Letters Pat. No. 4,501,927. In forming a seal according to this invention the O-ring and the sleeve are applied over the cables and the cables are spliced. Thereafter the sleeve is rolled along the cable to a position over both O-rings and over the spliced area of a cable. This is not a teaching of applying an O-ring seal to one end of a closure which is elliptical in section or at said one end.
The present invention affords an efficient protective seal for one end of a splice closure and is specifically adapted to sealing a pedestal splice in a loop of transmission cable to bring in a service wire. The resulting splice closure is reenterable and can again be sealed without tools or additional materials.